The invention relates to the use of smectite clays as dispersing agents for dye carriers in the dyeing of hydrophobic textiles.
Certain hydrophobic textiles such as polyester (polyethylene terephthalate, sometimes known as PET), triacetate and aramid textiles are difficult to dye with disperse dyes at temperatures below their glass transition temperatures (T.sub.g). Adequate dyeing rates are achieved when the dyeing temperature exceeds T.sub.g, and economic dyeing rates are achieved with high temperature dyeing (ca. 130.degree. C.). Adequate rates of disperse dyeing of hydrophobic textiles at lower temperatures can be achieved by the use of dye carrier compounds, sometimes referred to as dye assistants or accelerants (referred to herein by the term "dye carrier" or "carrier component"). Dye carriers have an affinity for and an ability to swell or plasticize the textile fibers and may be visualized as "carrying" the dye into the fibers. Dye carriers are typically low molecular weight, aromatic, hydrophobic organic oils that facilitate the dyeing process by plasticizing the surfaces of the fibers so that dye molecules can penetrate more rapidly and at lower temperatures. Examples of popular compounds for use as dye carriers in dyeing polyester textile material include aromatic and halogenated aliphatic hydrocarbons and phenols, such as o-phenylphenol, diphenyl or chlorinated benzenes, alkylphthalimide compounds, biphenyl, and o-chlorotoluene.
Effective carrier compounds are insoluble in the aqueous dye bath and are added to the dye bath as emulsions with the aid of a dispersing agent. Effective dispersing systems for carrier compounds must perform two functions: (1) the function of maintaining the organic carrier dispersed in an aqueous solution; and (2) the function of allowing the organic carrier to come into contact with the surface of the fiber. For some dispersing agents, these functions may be at odds with each other in that a strong dispersing agent may partition the carrier oil into the aqueous phase, allowing reduced contact with the hydrophobic textile.
The use of carrier agents in disperse dyeing of textiles is well known, including the use of alkylphthalimides and derivatives thereof. See for example U.S. Pat. Nos. 3,574,513, 4,780,105 and 4,994,089, and British patent 2,247,470, granted Mar. 4, 1992.
Many of the commonly used dye carrier formulations present health and environmental risks. While the use of dye carriers such as alkylphthalimides would minimize these risks, as well as objectionable odor of some previous carriers, performance versus cost concerns with previous alkylphthalimide carrier formulations have resulted in their being underutilized in the industry. Therefore, there is a long felt need for dye carrier formulations which are more acceptable as concerns safety and which deliver effective, efficient performance in the dyeing process.